starr



(No Model.)

E. T. STARR.

RHEOSTAT.

` No. 266,910. Patented O0t.31,1882.

UNIree tirarse Pett-teur @trice ELI T. STARR, OF PHILADELPHIA,IENNSYLVAITIA, ASSIGNOR 0F ONE-HALF TO WILLIAM J. PEYiUN, UF IASHING"ON,I). C.

RH EOSTAT.

SPECIFICATION forming part of Letters Patent No. 266,910, dated October31, 1882. Application filed September 4, 1852. (No model.) Patented inEngland July i3, 188'), No. @,330.

tion of electro-magnetic motors employed for driving light machinerysuchas sewing-machines, lathes, {wcwhereby the speed and power ofthe machineor machines being driven may be readily controlled by the operator.Various forms ot devices have heretofore been suggested for thispurpose, but none, so i'ar as I am aware, save that patented to me July4, 1882, as No. 260,623, are as simple and etlicient as is desirable.

The object ot' my present invention is to provide an improvedvariable.resistance circuitcontrolling device, which is simple,inexperisive, and exceedingly ettieient.

The subject-matter claimed is particularly pointed ont at the closeofthe specification.

Some of my innnoveinents may be used without the others and inconnection with electric circuits not includingelectro-magnetic motors.

The accompanying drawing` iliustrates my said improvements as organizedin the best way now known to me, the figure being a sectional elevationthrough the variableaesistance device.

A base or stand, A, is provided with binding-screws a c for connectingthe circuit-wires l 2, which lead to and from a batteryor othergenerator ot' electricity, said circuit including au electro-magneticmotor, it such is used.. Said binding-screws are in electrical connection, by wires 3 4, respectively, with the variable-resistance device,so as to constitute said device a part ofthe circuit. Saidvariable-resistance device consists of a vessel preferably composed oftwo telcscoping or expansible and contractible sections, C C', (saidsections being` also preferablyofnolrcon d ucting material,such as glassor hard rubber,) held apart by a coiled spring, @,the lower or basesection, C, being tirmly mounted upon the baseboard. and torining a cupor cell to contain a Huid offering comparatively high resistance to thepassage of an electric current.` A conducting` wire or rod, t?, projectstroni or is carried by the upper sliding section. (if, ot said vessel,so as to enter the ilnid in the. base-section G, and the depth to whichthis wire or conductor is made to enter the iluid controls theresistance to be oti'ered to the passage ot' the electric current, 6oand consequently the action ot' the current upon the electric motorincluded in the circuit. The wire I3 is connected with a binding-screw,

c, the upperend ot' which, in this example, enters slightly into theiiuid, so as to be in elecrical connection therewith and constitute aconductor, while the wire 4- is connected with the wire or conductor d,in tliisIiustanee, by way of the reacting spring c. rIhe section G ofthe fluid-containing vessel stands in its nor- 7o mal position at itsgreatest height relatively to the base-section U, with the end oftheconductor d at its greatest distance l'rom the end ci' theconducting-screw @,anil when in this position the nmxiinnin resistanceis oii'ercd to 7 the passage ot' the electric current through theresistance device. A treadle, F, pivoted upon the base-board A,connected at its front or toe end with the npperend ot' the slidingsection C ot' the duid-containing vessel, and the 8o connection ispret'erably made by a slot and pin, as t'ully shown and described in myai'oresaid patent, whereby upon depressing the treadle to vary theresistance ot the circuit the vesselsection U', carrying the conductord, 85 moves down upon the tixed vesselsection without lateral movement.The connection bctween the treadle and vessel, in other words, is

a sliding or yielding one, and such a connection may be madeinvariousways. Pressure upon 9o the treadle by lthe toot ot' the operatorcauses the conductor d to move into the resistancetlnid and approachnearer to the end of the screw or conductor c. The nearer said conductord approaches the conductor c the less resistance there is otiered to thepassage of the current, Aas will be obvious. The resistance in tbecircuit can consequently be varied as required, and tothe slightestdegree, simply by pressure of the foot, without breaking the roocircuit. As soon as the pressure is removed the spring c retracts theconductor d, and at the same time elevates the toe end ot the treadle,ready for a new depression, which is to vary the resistance offered tothe passage of the current.

It will be understood, of course, that the upper section, G, of thefluid-containing vessel need not be a closed section, although theconstruction shown is in most cases preferable.

'A spring (not necessary to be shown) may also he used under the treadleand disconnected from the duid-vessel, either as auxiliary to or inplace ofthe spring` c. I have deemed it unnecessary to show thesechanges in the dra'wing, as they and other changes may readily be madeby a skillful meclianician, and would not constitute a departure from myinvention.

I have thus descr1bed, as constructed in the hest way now known to me, aresistance device organized for use with a treadle or pivoted lever, bylwhich the resistance of an electric circuit may be varied by causingthe approach and recession of a conductor relatively to anotherconductor, said conductors being in contact with an intermediate mediumoffering higher resistance to the passage of the current than saidconductors.

I claim herein as of my invention- 1. The combination, substantially ashereinbefore set forth, with an electric circuit, ot' thevariableresistance device consisting ot' the vessel containing aresistance-duid and the conductors in contact with said fluid, one ot'said conductors heilig movable in the iuid t0- ward and from the other,the treadle to govern the approach ot' said conductors relatively toeach other, and a sprin g to return said treadle to its normal positionwhen the pressure thereon is removed.

2. The combination, substantially as hereinbefore set forrl1,ot' theeXpansible and contractible vessel, the sections of which are eachprovided with a conductor, the spring to nor mally maintain saidsections distended, and the resistance-fluid contained within saidvessel, in which said conductors are in Contact.

In testimony whereof' I have hereunto subscribed my name this 19th dayoi" July, A. D. 1882.

ELI T. STARR.

Witnesses:

E. EUGENE STARR, WM. J. PnY'roN.

